In a gas turbine combustion system, the combustion chamber or casing contains a liner which is usually of a sheet metal construction and may be of a tubular or annular configuration with one closed and one opposite open end. Fuel is ordinarily introduced into the liner at or near the closed end while combustion air is admitted through circular rows or apertures spaced axially along the liner. These gas turbiine combustion or combustor liners usually operate at extremely high temperatures and depend to a large extent on incoming combustion air from an appropriate compressor for liner cooling purposes.
As a consequence of high temperature cyclic operation and existence of thermal gradients, severe liner cracks appear about the circumference of some of the liner combustion air holes leading to premature repair and sometimes to failures necessitating replacement of the liner.